Photographic processes and elements comprising integral color correction mask-forming compounds



United States Patent Oflice 3,525,614 Patented Aug. 25, 1970 3,525,614 PHOTOGRAPHIC PROCESSES AND ELEMENTS COMPRISING INTEGRAL COLOR CORRECTION MASK-FORMING COMPOUNDS Jan Jaeken, Hove, and Frans Philomena Serrien, Wilrijk, Belgium, Paul Marx, Leverkusen, Germany, and Marcel Karel Van Doorselaer, Gravenwezel, Belgium, assignors to Gevaert-Agfa N.V., Mortsel, Belgium, a Belgian company No Drawing. Filed Sept. 19, 1967, Ser. No. 668,922 Claims priority, application Great Britain, Sept. 19, 1966, 41,637/ 66 Int. Cl. G03c 7/18 U.S. Cl. 96-9 12 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process and a material for the manufacture of photographic colour images and more particularly to a process of colour correction utilizing an integral masking procedure.

It is known that dyes formed by colour development in subtractive multicolour photographic images do not possess the desired absorption spectrum. The cyan dye, which should absorb red light and transmit green and blue light, usually absorbs a major proportion of red light but unfortunately also a minor amount of green and blue light. The magenta dye which should absorb green light and transmit blue and red light, usually absorbs a major p portion of green light but unfortunately also a minor amount of blue and red light. The yellow dye, which should absorb blue light and transmit green and red light, is usually satisfactory.

Owing to the above unwanted side-absorptions of the dyes formed on colour development it is impossible to obtain a true photographic reproduction of the original colours. Correction of the colours on printing multicolour photographic negatives is therefore desirable and this is usually done by masking the unwanted side-absorptions. This masking mainly relies on the formation of a mask image, i.e., an image with opposite gradation in respect of the primary dye image formed on development with a colour that corresponds with the side absorptions of the primary dye image.

Several masking processes have been proposed hitherto for eliminating the deficiencies in colour tone of photographic dyes owing to their side-absorptions. The most interesting among them are those wherein the mask can be produced in the photographic material itself, i.e., the so-called integral masking processes.

A process for the production of a photographic colour image wherein the mask is integral with the coloured image is described, e.g.,, in the UK. patent specifications Nos. 975,932 and 993,749.

According to said patent specifications a colour corrected image is formed in a photographic element comprising at least one silver halide emulsion layer containing a colour coupler for cyan or for magenta, which on development by reaction with the oxidation product of an aromatic amino developing agent forms a primary dye image, which absorbs a major proportion of light in the red or green region respectively of the visible spectrum and undesirably absorbs a minor proportion of light in the blue and green or in the blue and red regions respectively of the visible spectrum, by treating said photographic element after image-wise exposure and colour development with an oxidizing alkaline bleaching solution, e.g., a photographic bleaching bath, in the presence of a mask-forming compound which after oxidation couples with the residual colour coupler whereby a secondary dye image is formed having a gradation opposite to that of said primary dye image and absorbing light in at least one of said unwanted minor absorption regions.

With the amidrazone mask-forming compounds specifically described in said UK. patent specification No. 975,932 mask images are obtained showing a good gradation but being of restricted practical use owing to their instability to light. The sulfonyl and acyl hydrazone mask-forming compounds specifically described in said UK. patent specification 975,932, e.g., 3-ethylbenzothiazolone-cetylsulphonyl-hydrazone are also of little practical importance, particularly when used with pyrazolone colour couplers, because they form mask images with rather low mask gradation. The mask-forming compounds of the said UK. patent specification No. 993,749 form mask images with a better mask gradation but they form in addition to the mask image a yellow overall colouring without masking effect owing to auto-oxidation of the maskforming compound.

According to the present invention mask-forming compounds are used for the production of colour corrected images analogously to the process described in the above specifications but with which the above disadvantages do not occur. The mask-forming compounds of use according to the present invention correspond to the following general formula:

COORs wherein:

R represents a hydrogen atom or a substituent, preferably an electron withdrawing substituent, e.g.,

R represents an alkyl radical or an aryl radical,

R represents a hydrogen atom, an alkyl radical or an aryl radical, and

D represents a radical rendering the molecule fast to diffusion, e.g., an aliphatic radical comprising a linear chain of at least 5 and at most 20 carbon atoms.

The following are preparations of some examples of benzothiazolone-Z hydrazone mask-forming compounds corresponding to the above general formula.

PREPARATION 1 3 Methyl benzothiazolone 2 (3 carboxy 4 hexadecyloxyphenyl)sulphonyl-hydrazone having the following structural formula:

is prepared as follows:

(a) Z-mercapto-benzothiazole is methylated to form 2- methyl-mercaptobenzothiazole whereupon the latter product is quaternised :by means of dimethylsulphate to form 2-methylrnercapto-3methyl-benzothiazoliummethylsulphate according to R. Riemschneider, Monatsh. 91 626 (1960).

(b) 15.35 g. (0.05 mole) of the quaternary compound and 22.8 g. (0.05 mole) of 3-carboxy-4-hexadecyloxybenzenesulphonylhydrazide prepared as described below are heated for 20 h. at 60 C. in 250 ml. of pyridine. The reaction product is poured into 750 g. of ice and 250 ml. of a concentrated hydrogen chloride solution. The precipitate formed is filtered by suction and washed with water. The mask-formingcompound corresponding to the above formula is recrystallized from acetic acid. Yield: 25 g. Melting point: 160 C.

The 3 carboxy 4 hexadecyloxy-benzenesulphonylhydrazide used was prepared by addition of a solution of 3 carboxy-4-hexadecyloxy-benzene sulphonylchloride in dioxan to an excess of hydrazine hydrate in dioxan at 10 C. After washing of the sulphonyl hydrazine precipitate with N hydrochloric acid and then with water, the product is recrystallized from acetonitrile. Melting point: 95100 C.

PREPARATION 2 '3-methyl-benzothiazolone-2 (2 hexadecyloxy 5 carboxyphenyl)-sulphonyl-hydrazone having the following general formula:

is prepared in an analogous way as the compound of preparation 1, using however 2-hexadecyloxy-5-carboxybenzenesulphonylhydrazide. The mask-forming compound obtained has a melting point of 189 C.

PREPARATION 3 3-methyl-6-sulpho-benzothiazolone 2 (3 carboxy 4- hexadecyloxy phenyl) sulphonylhydrazone having the following formula:

is prepared as follows:

(a) To 50 ml. of oleum (30% of free sulphur trioxide) 9 g. (0.05 mole) of 2-methylmercapto-benzothiazole are added gradually. Then the reaction mixture is kept for 1 h. at 100 C. After having poured the reaction mixture on ice, the precipitate formed is filtered by suction and boiled with ethanol. 11 g. of 2-methylmercapto-6-sulpho-benzothiazole are obtained with a melting point above 260 C.

(b) 2.61 g. (0.01 mole) of 2-methylmercapto-6-sulphobenzothiazole are melted at 160 C. for 24 h. together with 3.72 g. (0.02 mole) of methyl-p-toluenesulphonate. After washing with ether and then with acetone 3.6 g. of 2-methylmercapto-3-methyl 6 sulpho benzothi azolium toluenesulphonate are obtained.

(c) 22.4 g. (0.05 mole) of this quaternary salt are heated for 5 days with 22.8 g. (0.05 mole) of 3-carboxy-4- hexadecyloxy-benzene-sulphonylhydrazide in 100 ml. of pyridine at 80 C.

After having filtered the reaction mixture, it is poured in 500 g. of ice and 120 ml. of concentrated hydrochloric acid. The precipitate obtained is washed with water and boiled with acetonitrile. 19 g. of the mask-forming compound corresponding to the above formula are obtained. Melting point: above 260 C.

PREPARATION 4 3 methyl 5 sulpho benzothiazolone-g (3-earboxy- 4 hexadecyloxy phenyl)-sulphonylhydrazone having the following structural formula:

I N COOH is prepared as follows:

(a) a suspension is made of 275.5 g. (1 mole) of 3-nitro- 4-chloro-phenylsulphonic acid potassium salt in 200 ml. of water whereupon the suspension obtained is heated to C. 960 g. (4 mole) of crystalline sodium sulphide are dissolved in 500 ml. of hot water and saturated with 136 g. of hydrogen sulphide. The sulphide solution is added between 80 and C. dropwise to the first solution and this very carefully because of the exothermic reaction. The mixture is cooled to 40 C. whereupon 80 ml. (1.2 mole) of carbon disulphide are dropwise added and the mixture is then heated for 1 h. at 60-65 C. and for 5 h. at 95 C.

At 50 C. the reaction mixture is acidified by means of 550 ml. of acetic acid. After addition of 500 ml. of water, Z-mercapto-benzothiazole-5-sulphonic acid potassium salt crystallizes upon cooling. After recrystallization from water, 268 g. of product are obtained having a melting point of above 260 C.

(b) the whole amount of this product is dissolved together with 79 g. of potassium hydroxide in 565 ml. of water at 60 C. After dropwise addition of 99 ml. of dimethyl sulphate the reaction is continued for 1 h. at 60 C. After acidification by means of 200 ml. of a concentrated hydrogen chloride solution and cooling to 50 C., 2-methylrnercapto-5-sulpho-benzothiazole crystallizes. After washing with ethanol, dissolving in a little water, and addition of 250 ml. of a concentrated hydrogen chloride solution, 175 g. of product are obtained with a melting point above 260 C.

(c) 52 g. (0.2 mole) of this product is quaternized by heating for 4 days at C. together with 40 g. (0.24 mole) of methyl-p-toluenesulphonate. Thesolidified mass is washed with acetone and 43 g. of 2- methylmercapto 3 methyl-S-sulpho-benzothiazolium p-toluenesulphonate are obtained with a melting point above 260 C.

(d) 44.7 g. (0.1 mole) of this quaternary salt and 45.6

g. (0.1 mole) of 3-carboxy-4-hexadecyloxy-benzenesulphonylhydrazide are heated for 48 h. at 60 C. in ml. of pyridine and 100 ml. of piperidine.

HOas

The mixture is poured into ice and hydrochloric acid and the precipitate obtained is filtered by suction, washed with water and then boiled with acetonitrile. 18.5 g. of mask-forming compound corresponding to the above formula are obtained with a melting point above 260 C.

PREPARATION 5 is prepared in an analogous way as the mask-forming compound of Preparation 4, starting however from 2- hexadecyloxy 5 carboxy benzene sulphonylhydrazide. Melting point: above 260 C.

PREPARATION 6 3 methyl 5 difluoromethylsulphonyl benzothiazot COOH lone 2 (3 carboxy 4 hexadecyloxy phenyl) sulphonylhydrazone having the following structural formula:

is prepared as follows:

(a) 2-mercapto-S-difluoromethylsulphonyl-benzothiazole is prepared in an analogous way as 2-mercapto-benzo thiazole-S-sulphonic acid potassium salt as described in Preparation 4 starting from 2-nitro-4-difluoromethylsulphonyl-chlorobenzene. Melting point: 234-236 C.

(b) 28.1 g. (0.1 mole) of this compound is dissolved together with 6.7 g. (0.12 mole) of potassium hydroxide in 150 ml. of ethanol. At 60 C., 10.4 ml. (0.12 mole) of dimethylsulphate are dropwise added and the reaction is continued for 1 h. at this temperature. After having poured out the reaction mixture in 1.5 l. of water the precipitate formed is filtered by suction, Washed with water and dried. 28 g. of Z-methylmercapto-S-difluoromethyl-sulphonyl-benzothiazole are obtained having a melting point of 127 C.

(c) 42 g. (0.143 mole) of this benzothiazole are melted with 32 g. (0.173 mole) of methyl-p-toluenesulphonate for 2 h. at 130 C. After Washing with acetone and then with ether 37.6 g. of Z-methylmercapto-3-methyl-5-difiuoromethylsulphonyl benzothiazolium p-toluenesulphonate with a melting point of about 210 C. (decomposition) are obtained.

(d) 37.6 g. (0.078 mole) of this quaternary salt are allowed to react for 12 h. at 60 C. with 35.7 g. (0.078 mole) of 3-carboxy-4-hexadecyloxy-benzenesulphouylhydrazide in 130' ml. of pyridine. The reaction mixture is poured on a mixture of ice and hydrochloric acid and the precipitate formed is filtered by suction, washed with water and recrystallized from isopropanol. Yield: 23.5 g. Melting point: 185 C. After a second recrystallization from isopropanol the melting point is 199 C.

PREPARATIONS 7-10 According to the method described by H. Passing, J. Pr. Chem. 153, 1 (1939) a secondary aromatic amine, e.g., diphenylamine is converted into the corresponding arylthiourea and then oxidatively converted by means of bromine in chloroform or acetic acid into a 2-imino-3- substituted benzothiazole. When starting from a primary aromatic amine a Z-amino-benzothiazole is obtained which can also be converted by alkylation in a 2-amino-3- substituted benzothiazole. By a subsequent nitrosation and decomposition by means of phosphorus pentasulphide in pyridine a 3-substituted benzothiazole-Z-thione is obtained according to Passing. According to this method the following compounds could be obtained:

3 phenyl benzothiazole 2 thione (H. Passing)-melting point: 98 C.

3-methyl-6-sulpharnido-benzothiazole -2 thione-melting point: 120 C.

3-methyl-6-fluoro-benzothiazole-2-thionemelting point:

3-methyl-6-chloro-benzothiazole-Z-thione--melting point:

These thiones are converted into the corresponding 2-methylmercapto-benzothiazolium compounds by melting with methyl-p-toluenesulphonate or by heating with methyl iodide in acetone. By heating these quaternary salts with a sulphonylhydrazide in pyridine, e.g., for 20 h. at 60 C., the desired mask-forming compounds are formed:

3-phenyl-benzothiazoIone-2 (Z-hexadecyloxy-S carboxyphenyl)-sulphonylhydrazone with melting point: 170 C. (decomposition).

3-methyl-6-sulphamido-benzothiazolone-2 (3-carboxy-4- hexadecyloxyphenyl) -sulphonylhydrazone with melting point: 142 C. 3-methyl-6-fiuoro-benzothiazolone-2 (2-hexadecyloxy-5- carboxyphenyl) sulphonylhydrazone with melting point: 186 C., and 3-methyl-6-chloro-benzothiazolone-Z (Z-heXadecyloxy-S- carboxyphenyl) sulphonylhydrazone with melting point: 181 C.

PREPARATION 11 3-methyl-4,6-dichloro-benzothiazolone-2 (2-hexadecyloxy-S-carboxyphenyl)-sulphonylhydrazone having the following structural formula:

S ()(CH2)15CH3 o1 C=NNH S 02- l \N (I) 0 ON 01 (7H3 is prepared as follows:

(a) analogously to the method described in Organic Syntheses Col. vol. III 735, 2,4-dichloroaniline is converted by means of benzoyl isothiocyanate into 2,4-dichlorophenylthiourea with a melting point of 163 C.

(b) to a suspension of 11 g. (0.05 mole) of this thiourea in ml. of chloroform a solution of 12 ml. of bromine in 20 ml. of chloroform is dropwise added at 5 C. After boiling for 15 min. the solvent is removed by evaporation. The residue is Washed with an ammonium hydroxide solution and recrystallized from acetonitrile. 4.4 g. of 2-amino-4,6-dichloro-benzothiazole are obtained having a melting point of 270 C. (decomposition).

(c) this benzothiazole is quaternized by heating it for 2 days at C. with methyl-p-toluenesulphonate. By Washing with acetone the quaternary salt solidifies.

(d) 12 g. (0.03 mole) of this quaternary salt are heated for 2 h. on an oil bath of 140 C. together with 15 m1. hydrazinehydrate in 60 ml. of ethylene glycol monomethylether. Upon cooling, 5 g. of 3-methyl-4,6-dichloro-benzothiazolone-2 hydrazone are obtained having a melting point of C.

Analogously to the method described by S. Hiinig, Ann. 623, 199 (1959), 2.48 g. (0.01 mole) of the above hydrazone and 0.44 g. of zinc oxide in 15 ml, of N-methylpyrrolidone are admixed under a nitrogen atmosphere with 4.6 g. (0.01 mole) of 2-hexadecyloxy-S-carboxybenzenesulphonylchloride in 10 ml. of N-methyl-pyrrolidone. By heating for 90 min. at 90 C. all products dissolve. Then 70 ml. of water and 20 ml. of'concentrated hydrochloric acid are added to the reaction mixture. The precipitate formed is washed with water and then recrystallized first from ethanol and then from acetonitrile. 3.3 g. of the mask-forming compound with the above structural formula are obtained having a melting point of 197 C.

PREPARATION 12 3-methyl-5-trifluoromethyl-benzothiazolone-Z (2-hexadecyloxy-S-carboxy-phenyl) sulphonylhydrazone having the following structural formula:

is prepared as follows:

brown solution is obtained. This solution is kept at 75 C. and added dropwise to a boiling solution of 49 g. of 2-chloro-5-trifluoromethyl-nitrobenzene in 100 ml. of ethanol. Boiling of the reaction mixture is continued for 3 hours whereupon the reaction mixture is cooled and the precipitate filtered by suction. The bis(2-nitro- 4-trifluoromethyl-phenyl)-disulphide obtained is washed with hot water and with methanol. Yield: 38 g. Melting point: 149l53 C. (crude product).

(b) 22.2 g. of this disulphide are suspended in 42 ml. of

glacial acetic acid and 18 ml. of concentrated hydrochloric acid. The suspension is heated in a 500 ml. three necked flask to 70 C. while stirring whereupon 32.5 g. of zinc dust are carefully added. The temperature rises to 110 C. The acid that has evaporated is replenished with the corresponding amount of fresh glacial acetic acid, whereupon once again 4.6 g. of zinc dust are added. The acid occasionally evaporated is now replenished by addition of concentrated hydrochloric acid. The reaction mixture is filtered by suction and the hot filtrate is poured, while stirring, into 500 ml. of water. The yellow precipitate formed is filtered by suction and washed till neutral.

() 12 g. of this yellow precipitate are suspended .in a sodium ethylate solution prepared by dissolving 1.05 g. of sodium in 80 ml. of ethanol. Then 6.7 ml. of carbon disulphide are added dropwise at room temperature. The reaction mixture is heated, while stirring, for 1 hour on a steam bath and then filtered by suction while hot. The filtrate is diluted with water till 4 times its volume and neutralized with glacial acetic acid. The Z-mercapto-S-trifluoromethyl-benzothiazole precipitate formed is filtered by suction and dried. Melting point: 208211 C. (crude product).

(11) to a solution of 4.6 g. of 2-mercapto-5-trifiuoromethyl-benzothiazole in 26 ml. of 2 N sodium hydroxide 3.8 ml. of dimethyl sulphate are added at room temperature. After having stirred for 30 min. the crystallized product is filtered by suction. The dried product is heated with ml. of dimethyl sulphate at 150 C. whereupon it is cooled and admixed with abs. acetone. The precipitate is filtered by suction and dried. Yield: 3 g. Melting point: 193-195" C.

(e) a mixture of 18 g. of the quaternary salt obtained in step (d), 200 ml. of pyridine and 22 g. of 2-hexadecyloxy 5 carboxy-benzene sulphonylhydrazide is heated at 60 C. for 24 hours. The mixture is concentrated to one third of its volume by evaporation and cooled. By addition of 2 N hydrochloric acid the pH is adjusted to pH 3-4. The precipitate is filtered by suction and recrystallized from methanol. Melting point: 175-177 C.

PREPARATION 13 3-methyl 5 p chlorophenylsulphamoyl-benzothiazolone-2 (Z-hexadecyloxy 5 carboxy-phenyl)-sulphonylhydrazone having the following structural formula:

is prepared as follows:

8 PREPARATION 14 3-methyl-S-chloro-benzothiazolone-2 (2-hexadecyloxy- S-carboxy-phenyl)-su1phonylhydrazone having the following structural formula:

is prepared as follows:

(a) 8.5 g. of Z-methylmercapto-S-chloro-benzothiazole prepared from Z-mercapto-5-chloro-benzothiazole according to US. patent specification 2,499,628 of Lister A.. Brooks, issued Mar. 7, 1950, and 30 ml. of dimethyl sulphate are heated at C. After cooling the precipitate formed is filtered by suction. Melting point: -187 C.

(b) 10 g. of the quaternary salt obtained in step (a) and 13.3 g. of 2-hexadecyloxy-S-carboxy-benzenesulphonylhydrazide are heated for 24 hours in pyridine at 60 C. The reaction mixture is then further treated as de scribed in Preparation 12(c). Melting point: 178- 179 C.

PREPARATION 15 3-methyl-benzothiazolone 2 (2 hexadecycloxy 5- ethoxy-carbonyl-phenyl)-sulphonylhydrazone having the following structural formula:

is prepared by suspending the compound of Preparation 2 in ethanol and introducing hydrogen chloride in the mixture at 78 C. whereby the said compound dissolves gradually. The mixture is evaporated till dryness in vacuum and the residue is taken up in boiling methanol. By addition of 2 N sodium hydroxide the pH is adjusted to pH 7-8. The precipitate that forms upon cooling is filtered by suction and recrystallized from methanol. Melting point: 74-75 C.

The process according to the invention proceeds as follows: silver halide is reduced to silver at the exposed areas in a colour developing bath containing a primary amine aromatic developing agent which is at the same time oxidized. The oxidized developing agent reacts with the colour coupler and forms a dyestuif, whereas the mask-forming compound according to the invention is not affected. After colour development, the material is treated in the bleaching bath wherein the oxidative coupling of the mask-forming compound with the residual colour coupler still available at the nonexposed areas of the material takes place, whereby a coloured mask is formed having a gradation opposite to that of the dye image formed on colour development. Subsequently, the photographic colour material is washed with water, fixed and dried.

It has been found that the mask-forming compounds which are used in the present invention, are especially suited for forming, by oxidative coupling with a colour coupler for magenta belonging to the class of the pyrazolone colour couplers, a yellow mask image, which compensates the undesirable side-absorption in the blue part of the spectrum of the magenta coloured primary dye image obtained by colour development of said colour coupler for magenta.

It has further been found that the mask-forming compounds which are used in the present invention are also particularly suited for forming, by oxidative coupling with a colour coupler for cyan belonging to the class of the naphthol colour couplers, a red to magenta mask image, which compensates the undesirable side absorption in the blue and green part of the spectrum of the cyan coloured primary dye image obtained by colour development of said colour coupler for cyan.

The heterocyclic nucleus of the mask-forming compounds used in this invention allows enough possibilities for substitution to adapt the position of the absorption maximum of the masking dye and the intensity of the mask colour image at will. With the mask-forming compounds of use according to the present invention mask images are obtained that are fast to light, that have a good mask gradation and that do not give rise to the formation of an overall additional colouring without masking efiect.

By the wide choice of mask-forming compounds according to the general formula of the present invention it is possible to choose those that are best suited for each emulsion with regard to e. g., dispersibility, sensitivity, fogging, storing capacity of the emulsion, viscosity or adhesiveness to adjacent layers.

Pyrazolone colour couplers that are useful for obtaining a yellow coloured mask image by reaction with the mask-forming compounds according to the present invention are, e.g., those represented by the following general formula:

Ar represents a phenyl radical or a phenyl radical containing a water-solubilizing group such as a sulphonic acid group, and

D represents an aliphatic radical comprising a linear chain of at least and at most 20 carbon atoms.

OH a r-1) @j ONE-Q I souu X represents an oxygen atom, a sulphur atom, a NHCO group, a -NHSO group, a -N-alkyl group or a sulphonyl group,

Y represents a hydrogen atom or a halogen atom,

D represents an alkyl radical comprising a linear chain of at least 5 and at most 20 carbon atoms, preferably 14, 16 or 18 carbon atoms, and

M represents a hydrogen atom, an alkali metal atom or an ammonium group.

wherein:

Suitable colour couplers for cyan of the above general formula are, e.g.z

N- (Z-n-hexadecyloxy-S -sulpho-phenyl l -hydro-xy-2- naphthoic acid amine sodium salt,

N- (2-n-hexadecyloxy-5-sulpho-phenyl) l-hydroxy-4- chloro-Z-naphthoic acid amide sodium salt,

N-(2-n-hexadecylmercapto-S-sulpho-phenyl) -1-hydroxy- 2-naphthoic acid amide sodium salt,

N- 2-n-hexadecylmercapto-5-sulpho-phenyl) -1-hydroxy- 4-bromo-2-naphthoic acid amide sodium salt,

N- 2-n-hexadecylmercapto-5-sulpho-phenyl) -1-hydroxy- 4-chloro-2-naphthoic acid amide sodium salt,

N- (2-palmitoylamino-4-sulpho-phenyl) l-hydroxy-2- naphthoic acid amide sodium salt,

N- (Z-methyl-n-hexadecylamino-S -sulpho-phenyl) lhydroxy-4-chloro-2-naphthoic acid amide sodium salt,

N- (3-su1pho6-n-hexadecylsulphonyl-phenyl) l-hydroxy- Z-naphthoic acid amide sodium salt,

N- (3 -s'ulpho-6-n-hexadecylsulphonyl-phenyl -1-hydroxy- 4-chloro-2-naphthoic acid amide sodium salt,

N- 3 -sulpho4-n-hexadecylsulphonyl-phenyl) -1-hydroxy- Z-naphthoic acid amide sodium salt.

These colour couplers for cyan can be prepared, e.g., by condensation of l-hydroxy-2-naphthoic acid or one of its derivatives with one of the suitable aromatic amines according to British patent specification No. 983,648, filed May 8, 1961, by Gevaert Photo-Producten N.V.

Other colour couplers for cyan that are suitable for obtaining a red to magenta coloured mask image by reaction with the mask-forming compounds according to the present invention are, e.g., those described and claimed in our published Netherlands patent application 66/ 14341 filed Oct. 12, 1966.

For carrying out the process according to the present invention, the colour couplers and mask-forming compounds can be incorporated into a photographic silver halide emulsion prepared by means of the colloids usually employed therefor, such as gelatin, polyvinyl alcohol, collodion or other natural or synthetic colloids. The silver halide emulsion may further contain usual ingredients, e.g., hardeners, chemical and optical sensitizers, plasticizers, development accelerators, stabilizing agents and Wetting agents. The silver halide emulsion is coated on a transparent support consisting of glass, nitrocellulose, cellulose, cellulose esters such as cellulose triacetate, polyester, polystyrene or another natural or synthetic resin, and forms part of a photographic material with one or more emulsion layers.

A multilayer material usually comprises the following elements: a support, a red-sensitized emulsion layer having a colour 'coupler for cyan, a green-sensitized emulsion layer having a colour coupler for magenta and a blue-sensitive emulsion layer having a colour coupler for yellow. There is a yellow filter, composed in most cases of a gelatin layer containing dispersed colloidal silver, located between the blue-sensitive emulsion layer and the green-sensitized emulsion layer. It is not only possible to incorporate the colour coupler and mask-forming compounds into the light-sensitive silver halide emulsion layer itself but they can also be incorporated into an adjacent nonlight-sensitive colloid layer or into a nonlightsensitive layer which is separated from the light-sensitive emulsion layer by a water-permeable colloid layer.

The following aromatic amino compounds can be used as developers for such material: diand triamino-aryl compounds, more especially N:N-dialkyl-p-phenylenediamines, such as NzNkliethyl p phenylenediamine and N:N-diethyl-Z-methyl-p-phenylene diamine, and deriva tives thereof such as N,N-dialkyl-N'-sulphomethylor N:N-dialkyl-N'-carboxymethylp-phenylene diarnine.

The bleaching bath generally contains potassium bromide, borax, magnesium sulphate and potassium hexacyanoferrate (III).

The following examples illustrate the invention.

EXAMPLE 1 225 g. of a photographic light-sensitive silver bromoiodide (2 moles present of iodide) emulsion comprising per kg. g. of gelatin and an amount of silver halide corresponding to 50 g. of silver nitrate, are melted with ml. of water at 40 C. Then the following ingredients 1 1 are added successively: 3.6 g. of l-(p-hexadecylsulphonylphenyl -3 2-sulphobenzamido -2-pyrazolin-5-one (see U. K. Patent specification No. 1,044,959 filed Oct. 10, 1963, by Gevaert Photo-Producten N.V.) dissolved in 3.6 ml. of 2 N sodium hydroxide and 32.5 ml. of water,

2.5 g. of 3-methyl-benzothiazolone-2 (3-carboxy-4-hexadecyloxy-phenyl)sulphonylhydrazone (Preparation 1) dissolved in 5 ml. of 2 N sodium hydroxide, 5 ml. of

ethanol and ml. of Water.

After acidification with acetic acid to pH 6 and after addition of the usual hardeners, stabilizers and coating aids, the necessary amount of water is added to obtain a coatable emulsion. The coatable emulsion is then coated onto a suitable support. The material thus obtained is exposed through a grey step Wedge and developed for 9' min. at C. in a developing bath having the following composition:

Grams Sodium hexametaphosphate 2 N,N-diethyl-p-phenylenediamine chlorohydrate 3 Sodium sulphite 4 Sodium carbonate 57 Hydroxylamine chlorohydrate 1.5

Potassium bromide 1 Water to 1000 m1. (pI-I=l0.6).

After having rinsed the material for 5 min. it is fixed for 5 min. at 20 C. in the folowing fixing bath:

Grams Sodium thiosulphate 200 Sodium bisulphite Potassium alum 20 Sodium biacetate 20 Boric acid 7.5

Water to 1000 ml. (pH=4).

After rinsing the material is bleached at 20 C. for 5 min. in a bleaching bath having the following composition:

Grams Potassium hexacyanoferrate (III) 100 Potassium bromide 15 Borax 20 Magnesium sulphate 50 Water to 1000 ml. (pH=8.6).

Then the material is rinsed again and fixed for 5 min. at 20 C. in the following fixing solution:

Grams Sodium thiosulphate 130 Borax 20 Magnesium sulphate 50 Water to 1000 ml. (pH=8.9).

Finally, the material is once again rinsed for 10 min. whereupon it is dried.

An image is obtained consisting of a magenta coloured wedge image and a yellow coloured 'wedge image. The yellow coloured wedge image has a gradation opposite to that of the gradation of the magenta coloured Wedge image and thus compensates the undesirable side-absorption of the magenta dye in the blue part of the visible spectrum.

EXAMPLE 2 225 g. of a photographic light-sensitive silver bromoiodide (2 moles percent of iodide) emulsion comprising per kg. 80 g. of gelatin and an amount of silver halide corresponding to 50 g. of silver nitrate, are melted with 150 ml. of water at 40 C. Then the following ingredients are added successively:

3.6 g., of N (2 hexadecyloxy 5 sulpho-phenyl) 1- hydroxy-2-naphthoic acid amide sodium salt dissolved in 3.6 ml. of 2 N sodium hydroxide and 32.5 ml. of Water,

2.5 g. of 3 methyl 5 difluoromethylsulphonyl-benzothiazolone 2 (3-carboxy 4 hexadecyloxy phenyl) sulphonylhydrazone (Preparation 6) dissolved in 5 ml.

12 of 2 N sodium hydroxide, 5 ml. of ethanol and 15 ml of Water.

After acidification with acetic acid to pH 6 and after addition of the usual hardeners, stabilizers and coating aids, the necessary amount of water is added in order to obtain a coatable emulsion which is then applied to a suitable support.

The material thus obtained is exposed through a grey step wedge and further processed as described in Example 1.

An image is obtained consisting of a cyan coloured wedge image and a red coloured wedge image having a gradation opposite to that of the gradation of the cyan wedge image. The red wedge image compensates the undesirable side-absorptions of the cyan dye in the green and blue parts of the visible spectrum.

EXAMPLE 3 A photographic multilayer material comprises the following layers in the indicated sequence: a support, a redsensitized emulsion layer as described in Example 2, a green-sensitized emulsion layer as described in Example 1, a yellow filter layer and a blue-sensitive emulsion layer comprising a colour coupler for yellow.

This material is exposed to a multicolour original, and then processed as described in Example 1. A masked negative image is obtained with which on printing through an appropriate filter, the undesirable side-absorptions in the blue and green part of the spectrum by the cyan dye and in the blue part of the spectrum by the magenta dye are eliminated.

What we claim is:

1. In a method of forming a colour-corrected image in a photographic element comprising at least one silver halide emulsion layer containing a colour coupler for magenta, which is reactive with the oxidation product of an aromatic amino developing agent to form by colour development a magenta primary dye image, which absorbs a major proportion of light in one region of the visible spectrum and undesirably absorbs a minor proportion of light in at least one other region of the visible spectrum, in which method said element is exposed to said image to be photographed, developed with said developing agent and thereafter treated with an oxidizing solution, the improvement which comprises carrying out said development and said treatment in the presence of a mask-forming compotmd corresponding to the following general formula:

R is hydrogen or an electron-withdrawing substituent, R is an alkyl group or an aryl group,

R is hydrogen, an alkyl group or an aryl group, and D is a group rendering the molecule fast to diffusion,

whereby the residual colour coupler oxidatively couples with said mask-forming compound to form a secondary dye image having a gradation opposite to that of said magenta primary dye image and absorbing light in at least one of said unwanted minor absorption regions but transmitting substantially all the light in the said major absorption region.

2. The method of claim 1, wherein the said colour coupler for magenta is a pyrazolone colour coupler.

3. The method of claim 1, wherein the said colour coupler for magenta is a pyrazolone colour coupler corresponding to the general formula:

Ar 1% =0 N H2JJii-D wherein:

Ar is phenyl or phenyl containing a water-solubilizing group such as a sulphonic acid group, and

D is an aliphatic radical comprising a linear chain of at least and at most 20 carbon atoms.

4. The method of claim 1 wherein said mask-forming compound is incorporated in the photographic element and the oxidizing solution is a photographic bleaching bath.

5. The method of claim 1 wherein said mask-forming compound is present in at least said one layer containing said colour coupler or in a colloid layer in water-permeable relationship therewith.

6. A photographic colour element useful in the method of claim 1, said element having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, at least one of said layers containing a colour coupler for magenta, which is reactive with the oxidation product of an aromatic amino developing agent to form by colour development a magenta primary dye image, which absorbs, a major proportion of light in one region of the visible spectrum and undesirably absorbs a minor proportion of light in at least one other region of the visible spectrum, such layer or a colloid layer in waterpermeable relationship with such layer containing a maskforming compound of the formula:

[R is hydrogen or an electron-withdrawing substituent, (R is an alkyl group or an aryl group,

R is hydrogen, an alkyl group or an aryl group, and D is a group rendering the molecule fast to diffusion,

said colour coupler for magenta also being reactive with the oxidation product of said mask-forming compound to form a secondary dye image having a gradation opposite to that of said magenta primary dye image and absorbing light in at least one of said unwanted minor absorption regions but transmitting substantially all the light in said major absorption region.

7. In a method of forming a colour-corrected image in a photographic element comprising at least one silver halide emulsion layer containing a colour coupler for cyan, which is reactive with the oxidation product of an aromatic amino developing agent to form by colour development a cyan primary dye image, which absorbs a major proportion of light in one region of the visible spectrum and undesirably a bsorbs a minor proportion of light in at least one other region of the visible spectrum, in which method said element is exposed to said image to be photographed, developed with said developing agent and thereafter treated with an oxidizing solution, the improvement which comprises carrying out said development and said treatment in the presence of a mask-forming compound corresponding to the following general formula:

L or) wherein R is a hydrogen or an electron-withdrawing substituent, R is an alkyl group or an aryl group,

R is hydrogen, an alkyl group or an aryl group, and D is a group rendering the molecule fast to diffusion.

formula:

0H X-D @j ONIFQ S 03M Y wherein:

X is oxygen, sulphur, NHCO--, NHSO;,-'-, a

group or sulphonyl group,

Y is hydrogen or a halogen atom,

D is an alkyl radical comprising a linear chain of at least 5 and at most 20 carbon atoms, preferably 14, 16 or 18 carbon atoms, and

M is hydrogen, an alkali metal atom or ammonium.

10. The method of claim 7 wherein said mask-forming compound is incorporated in the photographic element gnctlh the oxidizing solution is a photographic bleaching 11. The method of claim 7 wherein said mask-forming compound is present in at least said one layer containing said colour coupler or into a colloid layer in water-pen meable relationship therewith.

12. A photographic colour element useful in the method of claim 7, said element having superposed silver halide emulsion layers sensitive to different regions of the visible spectrum, at least one of said layers containing a colour coupler for cyan, which is reactive with the oxidation product of an aromatic amino developing agent to form 'by colourdevelopment a cyan primary dye image, which absorbs a major proportion of light in one region of the visible spectrum and undesirably absorbs a minor proportion of light in at least one other region of the visible spectrum, such layer or a colloid layer in waterpermeable relationship with such layer containing a maskforming compound of the formula:

wherein R is hydrpgen or an electron-withdrawing substituent, R is an alkyl group or an aryl group,

R is hydrogen, an alkyl group or an aryl group, and D is a group rendering the molecule fast to diffusion,

said colour coupler for cyan also being reactive with the oxidation product of said mask-forming compound to form a secondary dye image having a gradation opposite to that of said cyan primary dye image and absorbing light in at least one of said unwanted minor absorption regions but transmitting substantially all the light in said major absorption region.

References Cited UNITED STATES PATENTS 3,245,787 4/ 1966 Willens et al 969 16 3,245,788 4/1966 Jaeken et a1. 969 3,293,032 12/1966 Jaeken et a1. 9622 US. Cl. XJR. 

